Argentina's Juan Monaco beat fifth-seeded Sam Querrey 6-4, 6-4 of the United States on Friday in the U.S. Men's Clay Court Championship quarterfinals.

The 32-year-old Monaco won the event at River Oaks in 2012. He will face third-seeded Feliciano Lopez of Spain, a 6-2, 6-3 winner over American Tim Smyczek.

In the night quarterfinals, top-seeded John Isner of the United States faced South Korea's Chung Hyeon, and fourth-seeded defending champion Jack Sock played seventh-seeded Marcos Baghdatis of Cyprus.